I have a problem with loosing the tasks which my computer is running. I need to migrate from linux to windows, but I don't want my BOINC loosing its task, done, running or waiting for computation. Is there a way to save all of them and keeping running them on the new OS?

No. Tasks are registered against the computer they (are going to) run on. The computer ID that downloaded the work will also have to upload & report them.

No two computers can use the same hostID. In a computer ID the operating system is registered, so that the scheduler can send the correct science applications to that hostID. By switching from Linux to Windows you change operating system.

So the host you now run on will be getting a new hostID, due to the switch to a other OS. Meaning that the new hostID will not be able to upload any finished work registered to the old hostID.

You can either:
1. Set No New Tasks and run the cache empty, upload & report all work before switching to the other OS.
2. Set No New Tasks and abort all work in cache, then switch to the new OS. Jord

Ancient Astronaut Theorists can tell you that I do not help with tech questions via private message. Please use the forums for that.

SETI@Home would hardly notice you aborting a few tasks - they would be resent to someone else.
You just wouldn't get the credit for those you aborted.Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?